Steel sheets and other metal sheets which are subject to oxidation have to be protected against corrosion when stored either as wound coils or as uncoiled or cut sheets. Moreover, steel sheets are generally shaped by the user, for instance by stamping, and lubricating compositions are employed for the purpose of facilitating this shaping of the sheets.
Anti-corrosion compositions which are applied on the steel sheets to prevent corrosion during storage are known. Before being shaped by a stamping process, it is necessary to treat steel sheets with lubricating compositions. The application of different coatings at different stages is expensive and requires additional man power.
Proposals for obviating this drawback have been made, and the use of compositions which act both as anti-corrosion agents and as lubricating compounds have already been proposed. However, most of these known compositions exhibit a poor lubricating performance or produce stains on the treated sheets. For instance, the use of compositions containing soaps or unsaturated higher fatty acids, such as oleic acid, result in the formation of stains on the steel sheets. Other compositions, containing mineral oils, also have this drawback or are poor lubricants. The use of compositions containing polybutenes or similar polymers instead of mineral oils has been suggested, but these compositions do not meet the requirements which are presently required for the treatment of steel sheets. In particular, these compositions do not allow high production rates. Acceptable compositions must possess certain characteristics which are now required by the industry. The composition must be sufficiently fluid to be rapidly applied on the steel sheets. Moreover, the composition should be easily removable from the stamped sheets, after the sheets have been processed. Furthermore, some industries, such as the automotive industry, require that the compositions remain stable during thermal treatments of the coated steel sheets where the temperature may reach 140.degree. C. or higher.
There is thus a need for anti-corrosion and lubricating compositions which meet certain specific and stringent requirements. More particularly, the compositions must:
(a) confer an efficient protection against rust formation, during storage of metal steel both as coils or as unwound and stamped sheets; PA1 (b) must possess a lubricating action in order to facilitate the stamping of the sheets; PA1 (c) must remain stable at temperatures of about 140.degree. C. or higher; and PA1 (d) must be capable of being removed easily and completely from the sheets by usual solvents or alkaline solutions. PA1 (a) a mixture A containing from 65 to 95 weight % of a mineral oil having a viscosity in the range of 15.times.10.sup.-6 to 30.times.10.sup.-6 m.sup.2 / sec at 40.degree. C., and from 5 to 35 weight % of a basic calcium salt of an alkylaryl-sulphonic acid in admixture with another anti-corrosive compounds selected from the group consisting of a petrolatum oxidate, a calcium salt of petrolatum oxidate and a calcium salt of mahogany sulphonic acid; and PA1 (b) a mixture B, in an amount of 0.75 to 5 weight % based on the mixture A, said mixture B containing a saturated higher fatty acid having from 12 to 18 carbon atoms, a saturated non-ionic surface-active compound and a heat stable, anti-oxidizing phenolic compound.
Additionally, the anti-corrosion/lubricants compositions must be easily applied, non-toxic and inexpensive. The present invention aims to provide compositions which meet these requirements and possess these characteristics.